Gaming the system: record EV range!

who made this a sticky? when and why? is there any rhyme or reason?

 

I've read that the maximum speed for EV is 62 MPH, but in practice I find my speedometer is 2 MPH fast. In other words, the engine kicks on whenever I go over 60 MPH based on GPS indicated speed.

I always run EV mode at the beginning of my journey until the estimated remaining miles is down to 8 just so I have room for regen. It seems the car doesn't accept rapid regen when it's already near full capacity.

Avoid B mode unless your battery is fully charged. It converts more of the energy from your downhill coast into heat instead of applying it to charging. If you need to slow down, use the brake pedal which will increase the rate of regen (up to a point). Setting the normal cruise control will automatically apply the regen to regulate downhill speed, so it demands less attention from the driver to maximize regen potential.

If you are fully recharging your battery on the downhill portion, then more of the battery should be used during the ascent.

A mountain pass IS a pulse and glide. Your pulse, which is a high throttle opening, is the ascent up the mountain, and the glide, which is engine off coasting, is accomplished during descent.

In general, driving hills and mountains is more efficient than steady cruising on a flat highway.

I've read that B mode is a federal requirement that vehicles be able to slow down by revving the engine up. You're right that there is [usually] no point in using B mode.

 

300 miles on 3 kWh of electricity and 3.75 gallons of petrol at 55-60 mph.

How is that not astoundingly efficient ?

 

OP: superb!

I drive with the same techniques as you do in similar terrain and manage low 60s mpg in my Prius (v)agon, so perhaps 65 mpg in a regular Prius.

ICE spin consumes some 1.2 kW, so if we assume half your 6 hour drive was ICE off you saved 3.6 kWh. Your one time battery charge gave you another 3 kWh for a total 6.6 kWh advantage over a regular Prius. That is 0.2 gallons of liquid fuel at the wheels, or about 0.2/0.36 = 0.55 gallons saved in the tank. Your use of 3.75 gallons then would have been 4.3 gallons in a regular Prius, or 69.7 mpg.

Still better than I can manage, but most of your result is pretty easy to explain. Perhaps the low speed driving through towns you passed through explains some or all of the remaining difference.

Cheers!

 

Agree.
The low speed driving in EV through towns / heavy traffic was probably also needed in order to lower battery SOC in preparation to the next rolling hills section.

 

I believe (but have no proof for it) that in EV mode:
B position engine spin = D position friction brakes assist.
Meaning: whenever engine spins for whatever reason (battery temp, SOC, regen rate etc.) in B position (alone or plus brake pedal) - braking in D position will be over the max regen capabilities or limitations for the same conditions and will need friction brakes to assist.
Maybe B position is required by regulations, but it is there, it would be an oversight by Toyota not to take full advantage of it for regen in EV mode.

 

I was referring to the technique of preserving charge on uphills by using HV, and then building up the charge on the downhill via regeneration, for the express purpose of manufacturing huge EV numbers on the MDS display. I was not challenging the efficacy of the P&G technique.

 

The large EV numbers posted was a side-effect/artefact. His reason to enter EV mode on downhills was to keep the ICE from spinning at the speeds he was traveling. If the PiP would have let him stay in HV mode and not spin the ICE I presume he would have -- then he would not have had to fiddle with the EV button all day long. The impressive efficiency would then have showed up in the MPG rather than the EV miles counter.

Put another way, the PiP let him drive energy free or better on downhills and an average 50 mpg for all the other terrain combined.

Gaming (at least to me) would be a case of low MPG and high EV miles (or vice versa.) That did not happen here.

You cannot P&G over ~ 44 mph in a regular Prius. That is a PiP advantage, and that was his point.

 

Well we made the trip up and down the mountain today, wife driving and me working the buttons and shift knob. I used the strategy suggested by this group (thank you). I was less aggressive in using the EV/HV button and B gear, letting the PIP do its thing...but fooling it when appropriate. On the way up we averaged 37 mpg . On the way down we averaged 150 mpg . That is an average of 93.5 mpg! I arrived home with 2.5 miles left in my EV battery. I think I an do better than 93.5 mpg if I use my buttons and gears more judiciously. Thank you everyone!

 

No! Bad math! Back to school with you!

This is one reason why mpg sucks as a unit; you can't average mpg numbers. From an earlier post, you said it was about 40 minutes on the way up, and 40 mph on the way down. That's not quite enough information to figure out the total distance, but if I figure that it's 40 minutes at 40 mph, then that means it's about 25 miles up and 25 miles down. As proof, calculate the actual amount of gas used in each direction, then calculate mpg based off the total mileage and total fuel used:
25 miles / 37 mpg = 0.676 gallons used on the way up
25 miles / 150 mpg = 0.167 gallons used on the way up.
50 miles / (0.676 + 0.167 gallons) = 59.3 mpg average

For our foreign friends that use some form of unit that is "volume / distance" instead of our "distance / volume" - e.g. L/100km - this isn't a problem. For example, convert your miles per gallon to gallons per mile, and average them:
(1/37 gpm + 1/150 gpm) / 2 = 0.0168 gpm average
Now, invert that; 1/(0.0168 gpm) = 59.3 mpg average
Oh hey, would you look at that? It agrees with what I computed above!

Our foreign friends don't have to worry about all that inverting of units, since their units are already inverted from ours. They DO still have to worry about whether they're averaging two numbers that came from the same amount of distance, however. (You can't average the L/100km measured for 10 km with the L/100km for 100 km and get anything meaningful.)

 

In short - if it is the same distance you do not need the actual distance in order to average - in both units.
Just average consumption rate and not efficiency.

 

Good job.

People have trouble understanding why. I try to explain that the fractional distance to the calculated middle is not equal but that does not seem to help. It should however be clear that if the down trip used no fuel at all the trip mpg would be double 37, or 74 mpg. So ~90 is obviously not right.

Anyway,
Parameterization helps when you want to solve this number in your head:
We start with 37 mpg up and 150 mpg down,
And estimate that the two numbers differ about 4x

So we used x amount going down and 4x going up for a total of 5x use
On average half each way, so 2.5x going down.
150/2.5 = 150*0.4 = 60 mpg.

Good enough estimate until you get home
There is a somewhat simple trick to get to around 99.8% accuracy routinely but I don't want to scare anybody off with arithmetic.

 

The MPG display that shows only Gas MPG but ignores the power/money spent on the Electric Mile/kWh.
This never made sense to me.
Combining both energy sources into only one measurement is Bad Data.

The Volt also has this display. It maxes at +250 MPG but that is useless data, just like with a PIP.
And Volt owners obsess about that bogus number about as bad as PIP owners.

 

Would you have then obsess over 35-37 MPG ?

If a person bought a Volt hoping for efficient liquid fuel use they are going to be disappointed
If a person bought a Volt hoping for overall low energy per mile they are going to be disappointed

So they highlight liquid fuel consumption per mile and say they do not care how much electricity they consume. Take your pick of rationalization or short-sighted.

 

Here in the NW, electricity is 1/4 the cost of gasoline per mile, and is almost entirely from "renewable" sources. Electricity cost and environmental impact is so insignificant compared to gasoline that I can mostly ignore it. Getting better miles per Kwh is just something that appeals to my general fondness of efficiency, and has less to do with a desire to "save the world".

 

Re renewable electricity fraction: Not so great if you are in Portland

 

I'm in Vancouver, but everyone thinks Canada when I say that. Oregon overall has somewhere around 85% renewable electricity. Might be less this summer since it's been hot and the reservoirs are low.

 

From

Oregon Department of Energy Oregon's Power Mix

, PG&E:

 

Perhaps, unless you generate your own power with solar panels like I do.